The present invention relates to a processing apparatus and method for, for example, subjecting an object to be processed, such as a silicon wafer, to CVD and etching. More particularly, the invention relates to a processing apparatus and method involving irradiation of the surface of an object to be processed with ultraviolet light.
In fabrication of semiconductor devices, an object to be processed (hereinafter called merely a wafer), such as a semiconductor wafer, is subjected to various kinds of processes, such as oxidation and film formation, by use of a plurality of vacuum processing apparatus. Recently, there has been proposed a multi-chamber processing apparatus: which has a so-called cluster structure and which can perform a plurality of processes within a single apparatus.
The multi-chamber processing apparatus includes a vacuum transfer chamber serving as a central chamber, a plurality of vacuum processing chambers for performing various processes, and a cassette chamber for loading/unloading an object to be processed.
A transfer mechanism, such as a transfer arm, for transferring a wafer, and a mechanism for orienting a wafer are disposed within the vacuum transfer chamber. A space for transferring a wafer by means of the transfer arm must be provided within the vacuum transfer chamber. Accordingly the processing apparatus involves a problem in that its footprint (area occupied for installation) increases. Particularly, with the recent tendency toward increase in wafer size, this problem is worsening.
When the surface of a wafer to be processed has impurities, such as an organic substance, adhering thereto, defective semiconductor devices are likely to result at high probability. Therefore, the surface of a wafer must be subjected to various kinds of processes so as to be kept clean.
In order to clean the surface of a wafer to be processed, the surface is pretreated;. specifically, irradiated with ultraviolet light so as to decompose an organic substance adhering thereto. For example, Japanese Patent Application Laid-Open (kokai) No. 58726/1983 discloses an apparatus involving irradiation of the surface of a wafer with ultraviolet light. Specifically, a plasma reactor includes a ultraviolet-light irradiation unit disposed between a processing unit and an unloader. The ultraviolet-light irradiation unit irradiates the surface of a wafer with ultraviolet light each time a wafer held by a transfer arm passes the unit.
In the disclosed apparatus, the entire transfer section is enclosed by a housing, and after being loaded into the housing, a wafer is irradiated with ultraviolet light during the transfer step. Thus, the overall structure of the apparatus is complex.
Involvement of the step for loading a wafer into and unloading from the housing increases the total number of steps for processing a wafer, causing difficulty in improving throughput.
The present invention has been accomplished in view of the above-mentioned problems in the conventional processing apparatus. An object of the present invention is to provide a novel, improved processing apparatus capable of solving the above-mentioned problems and other problems.
To achieve the above object, according to a first aspect of the present invention, there is provided a processing apparatus comprising a transfer chamber, which comprises transfer means for transferring an object to be processed, and one or more vacuum processing chambers, which are disposed around the transfer chamber and adapted to process the object to be processed. The processing apparatus is characterized in that a pretreatment chamber for irradiating the object to be processed with ultraviolet light is disposed within the transfer chamber.
According to the present invention, the pretreatment chamber is disposed within the transfer chamber, thereby decreasing the footprint of the processing apparatus. Another processing chamber can be disposed at a peripheral space of the transfer chamber, which is conventionally occupied by a pretreatment chamber.
Since the pretreatment chamber is disposed outside an object transfer path extending between the transfer chamber and each of the processing chambers, a transferring operation effected by the transfer means is not obstructed, and the size of the transfer chamber remains unchanged. Since an object to be processed can be transferred directly from the pretreatment chamber within the transfer chamber to a processing chamber, the transfer distance of a transfer arm can be decreased as compared to the case where the pretreatment chamber is disposed outside the transfer chamber, thereby improving throughput.
In order to decrease the size of the pretreatment chamber through reduction of members to be disposed within the pretreatment chamber, it is preferable that ultraviolet-light generation means for generating ultraviolet light be disposed outside the pretreatment chamber, while an ultraviolet-light transmission window is provided on a wall of the pretreatment chamber so as to introduce ultraviolet light into the pretreatment chamber.
The pretreatment chamber may comprise gas supply means for supplying thereinto a processing gas to be activated by ultraviolet light. In this case, contaminants adhering to an object to be processed can be removed not only through irradiation with the ultraviolet light but also by means of active atoms generated from the processing gas, thereby reliably performing decontamination.
Preferably, the pretreatment chamber comprises orienting means for orienting an object to be processed, thereby avoiding separate disposition of the pretreatment chamber and the orienting means within the transfer chamber. Accordingly, the size of the transfer chamber is decreased, thereby further decreasing the footprint of the processing apparatus. This configuration enables an object to be processed to concurrently undergo orientation and exposure to ultraviolet light, thereby improving throughput.
According to a second aspect of the present invention, there is provided a processing apparatus comprising a transfer chamber, which comprises transfer means for transferring an object to be processed, and one or more vacuum processing chambers, which are disposed around the transfer chamber and adapted to process the object to be processed. The processing apparatus is characterized in that an ultraviolet-light irradiation apparatus is disposed along an object transfer path extending between the transfer chamber and each of the processing chambers.
In this processing apparatus, the ultraviolet-light irradiation apparatus may be disposed in any of the following manners: above the object transfer path located within each of the processing chambers; above the object transfer path located within the transfer chamber; and above the object transfer path located within each of the processing chambers, as well as above the object transfer path located within the transfer chamber.
According to third and fourth aspects of the present invention, there is provided a processing method comprising a step of irradiating an object to be processed with ultraviolet light in the course of transfer of the object held by an arm between a processing chamber and a transfer chamber. The processing .method is characterized in that irradiation of the object with ultraviolet light is turned on and off synchronously with the operation of the arm.
Alternatively, an ultraviolet lamp is turned on and off synchronously with opening/closing of a door.
According to the present invention, the ultraviolet-light irradiation apparatus is disposed above the object transfer path, thereby irradiating an object to be processed with ultraviolet light efficiently and in a simple manner. Also, an object to be processed can be irradiated with ultraviolet light while being transferred swiftly.